The present invention relates to the low dielectric constant material having thermal resistance, an insulation film between semiconductor layers using the same, and the semiconductor device.
Along with improvement in speed and high integration of a semiconductor device, the problem of signal retardation has become serious. The signal retardation is expressed with the product of resistance R of a wire and capacity C between wires and between layers. In order to suppress the retardation to the minimum, it is an effective means to lower the dielectric constant of an insulation film between layers, as well as to lower resistance of wiring.
Recently, in order to lower the dielectric constant of an insulation film between layers, there is proposed a method for forming an insulation film between layers using a silicon oxide film (SiOF film) wherein the fluorine atom is incorporated. Moreover, since an organic compound material can relatively lower dielectric constant, there is proposed a method for forming an insulation film between layers by using a parylene deposit film or a polyimide film wherein a fluorine atom is incorporated (Hideki Shibata, Densijyouhoutsuusin Gakkaishi Vol. 80, No. 3 p235(1997)).
By the way, the dielectric constant of the insulation film between layers becomes lower than that of the conventional film, when the insulation film between layers is formed by the above SiOF film. However, a dielectric constant thereof becomes about 3.2 to 3.5, capacity between wires can not be reduced and signal propagation delay of wires can not be sufficiently prevented.
Moreover, the dielectric constant 2.7 is attained by using the film wherein the fluorine atom is incorporated into the polyimide and aryl ether polymer, when an insulation film between layers is formed with the organic compound material mentioned below. But it is not still sufficient. By using deposit film of parylene a dielectric constant 2.4 can be attained, but the process for preparing a semiconductor device is limited, since thermal resistance is only about 200 to 300° C.
The dielectric constant of 2.0 to 2.5 has been reported in porous SiO2 film. But there is a problem that mechanical strength (CMP polishing process resistance) is low due to high porosity, and a pore diameter varies.
Since thermal conductivity of these polymeric materials and porous SiO2 film is lower than that of the conventional insulation film between layers of SiO2, there is a problem that the wiring life is degraded (electromigration) by the wire temperature rise.
As mentioned above, the insulation film between layers has been desired, which has low dielectric constant and is excellent in thermal resistance, mechanical strength, and the thermal conductivity.
Concretely, in design-rule 0.13 to 0.10 μm, the film is required, which has mechanical strength and thermal conductivity not less than an SiO2 film, dielectric constant of at most 2.4, and thermal resistance (thermal decomposition temperature) of at least 450° C.